 Nonsynchronous operation provided by the Extended CKD ("ECKD") set of CCWs removed the gap timing constraint.The five additional ECKD CCWs are Define Extent, Locate Record, Write Update Data, Write Update Key and Data, and Write CKD Next Track.In nonsynchronous operation, the transfer of data between the channel and the storage control is not synchronized with the transfer of data between the storage control and the device.